Various medical devices have been developed that acquire information from one or more physiologic sensors or transducers. A typical physiologic sensor transduces a measurable parameter of the human body, such as blood pressure, temperature, or oxygen saturation, for example, into corresponding electrical signals. In many implantable medical device applications, it is often desirable or necessary to acquire physiologic data for extended periods of time and on a continuous basis. Moreover, in many applications, it is often desirable or necessary to provide for such extended periods of physiologic data acquisition through use of an apparatus that is both convenient for the patient to use and one which does not draw public attention to the patient's condition. It is well understood that conspicuous or easily noticed medical devices and equipment often provide a disincentive for patients to participate in needed testing, evaluation, and therapies.
A problem well known to designers of implantable medical devices, such as pacemakers, for example, concerns the necessity to use low power components, including low power memory components, within the implantable medical device. Use of low power components is considered necessary in order to provided for extended periods of implantable electronic device operation and to reduce the need to repeatedly replace batteries which can only be accomplished through surgical means. As a consequence, conventional implantable medical devices typically employ low voltage, low current memory devices which have limited storage capacity and access speed, and often lag behind the state-of-the-art in memory technology by several years. These and other limitations significantly decrease the data storage and access capability of implantable medical devices, and often precludes the opportunity to integrate high capacity, low cost, state-of-the-art memory devices in implantable medical device designs.
Various implementations of portable or user-worn electrocardiographic recording/monitoring devices are known in the art, examples of which may be found in the issued U.S. Patents listed in Table 1 below.
TABLE 1 Patent No. Inventor(s) Issue Date 5,759,199 Snell et al. Jun. 2, 1998 5,634,468 Platt et al. Jun. 3, 1997 5,511,553 Segalowitz Apr. 30, 1996 5,289,824 Mills et al. Mar. 1, 1994 5,191,891 Righter Mar. 9, 1993 5,113,869 Nappholz et al. May 19, 1992 4,622,979 Katchis et al. Nov. 18, 1986
The patents listed in Table 1 hereinabove are hereby incorporated by reference herein in their respective entireties. As those of ordinary skill in the art will appreciate readily upon reading the Summary of the Invention, the Detailed Description of Various Embodiments, and the Claims set forth below, many of the devices and methods disclosed in the patents identified below and listed above in Table 1 may be modified advantageously by using the teachings of the present invention.
A conventional portable or user-worn electrocardiographic (ECG) monitor/recorder, such as those disclosed in one or more of the patents listed in Table 1 above, typically requires an external harness to secure the device to a patient during use. Moreover, such conventional ECG monitoring devices are generally conspicuous and readily perceivable by others, and must typically be removed prior to exposure to water or other hostile environments. As was previously described hereinabove, an important and often necessary requirement for providing effective testing and evaluation is ensuring that the monitoring device will be worn by the patient during the entirety of the testing period.
An ECG monitoring/recording device which is conspicuous to onlookers creates a disincentive to wear such devices. Such conventional ECG monitoring devices must also be removed during bathing or swimming, thus interrupting the acquisition of data during these times. Also, conventional ECG monitoring/recording devices are limited in terms of their ability to acquire only electrocardiographic data obtained through contact with the patient's skin.